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The nature of sound

All the time we hear sounds from all sides. We hear sounds through our ears which are special receivers1 for sound just as our eyes are special receivers for light.

Where there is sound there is movement, i.e. all sounds are produced by something that vibrates.

Hearing is a very complicated process in which the ears and the brain cooperate. The ears act as detectors, amplifiers and converters. They detect sounds by picking up vibrations in the air. They amplify the sound by changing small pressures into larger ones. Then they convert it into electrical signals being carried to the brain. The brain performs the job of interpreting the signa.

Being made at a distance from us the sound has to travel across that distance to our ears. It is the air that is actually the carrier that brings the sound to our ears. Air is not the only medium that carry sound. Any gas, liquid or solid can serve as the material medium through which sound can pass.

But the sounds being heard by our ears are not the only ones that there exist. There are also sounds that we cannot hear. They are called ultrasonic sounds. Although we do not hear them we have learned how to make them and detect them. The study of sound has grown into two new areas - ultra­sonics and supersonics the prefix "ultra" means beyond. In ultrasonics it refers to the fact that we study and use sounds that have frequencies be­yond those we can detect with our ears.

The prefix "super" means above. In supersonics it points to the fact which deals with speeds above the speed of sound.

Grammar and lexical exercises

I. Define the Absolute Participial Complex and translate the sen­tences into Ukrainian.

1. There being no other traffic, the driver can maintain a constant speed of, say, 90 km/hr (kilometres per hour). 2. Part of energy being changed into heat, is transformed into electric energy. 3. The cyclotron may be regarded as a modification of the linear accelerator, the particles being transferred from one to the other at the proper instants by the action of a magnetic field. 4. The positive pole having been brought near the negative pole, the latter attract it. 5. Two bodies having potentials of 100 volts and 50 volts, a potential difference exist between them of 50 volts. 6. The current distribution over the cross section of the conductor being non-uniform, the resistance increases. 7. The travelled distance having been given in metres and the time in seconds, speed was measured in m.p.s., that is, in meters per second.

II. Translate the following sentences paying attention to the Abso­lute Participial Complex.

1. The fundamental of electricity are the fundamentals of electronics, both being branches of physics. 2. The condenser being placed in a direct currents circuit the current will stop flowing. 3 The velocity, lenght and frequency of the wave are independent of each other, the frequency being equal to the velocity divided by the wavelenght. 4. The size of the electrodes being increased, the current capacity also increases, the voltage output remaining the same.